Toggle lock for breech bolt



Sept. 19, 1961 R. s. ROBINSON 3,000,268

TOGGLE LOCK FOR BREECH BOLT Filed Sept. 12, 1952 3 Sheets-Sheet 1 3mm WP 1961 R. s. ROBINSON 3,000,268

TOGGLE LOCK FOR BREECH BOLT Filed Sept. 12, 1952 3 Sheets-Sheet 2 s z a7 3 3 )2 W T: T

Ill/I 7) W ATTORNEYS Sept. 19, 1961 R. s. ROBINSON 3,000,268

TOGGLE LOCK FOR BREE-CH BOLT Filed Sept. 12, 1952 3 Sheets-Sheet 3 m; 1ATTORNEYS 3,000,268 TOGGLE LOCK FOR BREECH BOLT Russell S. Robinson,Short Beach, Conn. (124 Via Yella, Lido Isle, Newport Beach, Calif.)Filed Sept. 12, 1952, Ser. No. 309,193 13 Claims. (Cl. 89-189) Thisinvention pertains to an improved mechanism by which the breech bolt canbe actuated and locked in recoil-operated firearms, the objects of theinvention being to provide a nearly ideal acceleration of the breechbolt at both ends of its reciprocation, to provide locking or secondarysupport for a directly locked bolt during the period of the explosion,and to make possible a shortened breech or inboard length.

The mechanism, according to the invention, is of the type in which thebreech bolt is interlinked to the barrel and to the gun casing by meansof a toggle lever and link system so that as the barrel reciprocatesduring firing, the breech bolt is constrained to move with respect tothe barrel whereby at each station of barrel movement in eitherdirection, the bolt is in a certain position with respect to the barrel.There are known bolt-actuating mechanisms of this type in which thetoggle members are disposed, when the bolt is forward, so as to besubstantially in line with the barrel axis, the recoil force beingtransmitted in such cases either via the toggle members to the fulcrumpoint supported in the barrel extension, or via one of the togglemembers to lugs incorporated in the barrel extension. Thus, the membersof the boltactuating linkage in such known cases must be of heavyconstruction, which impairs their application to weapons of high ratesof fire and/ or heavy caliber. Furthermore, in such constructions, thelength of the breech is ruled largely by the fact that the togglemembers fold behind the breech bolt during recoil.

In bolt actuating mechanisms according to the invention the fulcrumpoint of said toggle members is displaced transversely with respect tothe barrel axis and may be located forward of the actuating point of thebreech bolt when the latter is in recoil position, thereby considerablyreducing the breech length of the firearm. Furthermore the operative endof the toggle lever may be set closer to the barrel axis than thefulcrum point of this lever when in recoil position, thereby reducingthe depth of the breech casing, and the breech bolt may be lockeddirectly ot the barrel extension, thereby permitting relatively lightconstruction of the actuating linkage.

Moreover, the location of the fulcrum point of the toggle members andthe arrangement of the latter provides that during final movement towardbattery position the toggle members lie at a substantial angle withrespect to the barrel axis (not in substantial alignment therewith) toapply a final transverse component of movement to the breech boltassembly which locks it directly to the barrel extension. This enablesthe construction of a firearm with less breech or inboard length tocontain the rearwardly folding toggle members than if they were insubstantial alignment with the barrel axis. Also the displacement of thefulcrum of the toggle lever away from the barrel axis enables the togglemembers to fold rearwardly, when in recoil, wholly upon one side of thebreech bolt thereby reducing the inboard length of the firearm and alsopreventing the sweeping of the toggle link into the space required forthe feed mechanism, if a belt feed or other feed means is applied to thetop side of the firearm.

One example according to the invention and two alternative lockingsystems applicable to it are described by reference to the followingdrawings:

FIG. 1 shows a vertical section passing through the nited States Patentamass Patented Sept. 19, 1961 the rising heel type, the barrel beingshown in recoiled' position;

FIG. 2 shows a similar section in which the barrel is in run-out(battery) position with the bolt forward and fully locked;

FIG. 3 is a similar sectional view showing the barrel in an intermediateposition;

FIG. 4 is a sectional view on line 44 of FIG. 1;

FIG. 5 is a sectional view on line 5-5 of FIG. 1;

FIG. 6 is a view similar to FIG. 1 showing a modified form of myinvention;

FIG. 7 is a sectional view on line 7-7 of FIG. 6;

FIG. 8 is a sectional view on line 8-8 of FIG. 6; and

FIG. 9 is a transverse sectional view showing a further modification.

Referring to FIG. 1, the firearm comprises a gun casing 1, a barrelassembly comprising a barrel 2 and a barrel extension 3, which aremutually fixed together by a thread 4. The barrel assembly is free toslide longitudinally in the gun casing through a limited distance, whichis definable by its respective positions in FIGS. 1 and 2, the barrel 2and a lug 5 on the bar-rel extension 3 sliding respectively in a ringguide 6 and a guide groove 7 constructed within the gun casing 1. Thebarrel extension 3 is urged forward by a diagrammatically shownrecuperator spring 8 which reacts rearwardly against the gun casing 1,and this extension includes two, spaced, substantially parallel, plates3* and 3.

Upon the adjacent surfaces of the plates 3 and 3 are oppositelydisposed, inwardly facing grooves 9, which are sloped in thisconstruction with respect to the axis of the barrel 2, and which supportand guide the breech 1 bolt 10 during its reciprocation in the barrelextension 3. At the forward end of the grooves 9 and let into theirupper surfaces are oppositely disposed recesses 11, the rear abutments12 of which provide locking faces for supporting the locking heel 13 ofthe breech bolt 10. Under the heel 13 of the bolt 10 are a pair of lugs14 to which is pivoted the forward end of a toggle link 15 by means of apin 16. The rear end of the link 15 is pivoted to the outer and forkedend of a toggle lever 17 by means of a pin 18. The fulcrum pin 19 of thelever 17 is oscillatably supported in the barrel extension 3 at asubstantial distance from the axis of the barrel, the axis of thefulcrum pin 19 being so located in the barrel extension 3 that when thelever 17 and link 15 are in substantial alignment, the locking heel 13of the breech bolt 10 is fully engaged with the abutments 12. On theopposite end of the toggle lever 17 is a stub lever 20 which is at anangle to the body of the lever 17 and which supports a pin 21, thecenter line of which, with respect to the fulcrum pin 19 axis, is at asubstantial angle with respect to the center line between the axis ofpin 18 and the fulcrum pin 19. The stub lever pin is pivoted to one endof an actuator link 22, the opposite end of which is oscillatably pinnedby a pin 23 to a pair of lugs 24, which are incorpoarted in the base ofthe gun casing 1. The position of lugs 24 is such that when the barrelis in full forward position, as shown in FIG. 2, the axis of link 22 issubstantially perpendicular to the barrel axis. Furthermore, in thatsame condition, a line joining the centers of pins 19 and 21 is slopedWith respect to the barrel axis so that pin 21 is closer to the barrelaxis than the fulcrum pin 19. A stop 25 in the barrel extension 3engages the lever 17 and prevents it from passing too far beyond deadcenter when the mechanism is in run-out position, as in FIG. 2.

In order to control the front end of the breech bolt 10 and prevent itfrom rising partly into the recesses 11 of the barrel extension 3 Whilstmoving near its forward limits, an opposite pair of laterally extendingguide lugs 26 are provided on the front of the body of the breech boltwhich are slidably accommodated in grooves 27 in the plates 3 and 3which run the length of the bolt guide grooves 9, the under side ofgrooves 9 and 27 lying in the same plane. By means of this construction,the front end of the bolt 10 is constrained to follow the path of theguides 27 and 9 throughout the full length of its movement, whereas therear end is enabled to rise to perform locking when the bolt is clear ofthe upper surface of groove 9 and in alignment with recesses 11.

The functioning of the above mechanism is understood by reference to thecasing 1 in FIGS. 1, 2 and 3. As the barrel extension 3 acceleratesforward under the influence of the recuperator 8 from the position shownin FIG. 1, the breech bolt 10 is constrained by the members of thelinkage 15, 17 and 22 to move forward with considerably greateracceleration until after the barrel extension 3 has traveled more thanhalf the distance between recoil and run out as shown in FIG. 3. Duringthe remainder of the run out of the barrel extension 3, the said linkagethen constrains the breech bolt 10 to decelerate, until by the time ithas reached its forward limit of movement with respect to the barrelextension 3 as indicated in dotted lines in FIG. 1, its relativevelocity with respect to the barrel extension 3 is low. The finalforward movement of the barrel extension 3 to the position shown in FIG.2 results in the raising of the heel 13 of the breech bolt by finalaction of the said linkage into the locking recess 11. During the recoilmovement of the barrel extensions from the position shown in FIG. 2 tothat shown in FIG. 1, the same functions occur to all members of themechanism as above described, but in reverse order.

Owing to the slope of the locking abutment 12, to facilitate the lockingof the breech bolt 10, there is a small component of force of theexplosion transmitted by the breech bolt It} to the barrel extension 3via the link 15 and lever 17 and their terminal pins 16 and 18, and thefulcrum pin 19.

The grooves 9 in the barrel extension 3, according to the above example,are shown as sloping with respect to the barrel axis. The grooves 5according to the invention may alternatively be parallel with respect tothe barrel axis without other than dimensional alteration to theconstruction as above disclosed.

Furthermore, the above construction uses a rising heel type of breechbolt. Other bolt-locking systems may be used within the scope and ambitof the invention such as systems using a breech bolt carrying a separatelocking piece, one typical example of which is shown in FIGS. 6 to 8, orsystems in which the breech bolt partially rotates to lock, one typicalexample of which is shown in FIG. 9.

Referring to the type of locking mechanism shown in FIGS. 6 to 8, thebreech bolt 40 is somewhat T-shaped in form and is provided withlaterally extending guide ribs 41 received in inwardly facing grooves 42in the barrel extension plates 3 and 3 which are substantially parallelwith the barrel axis. A locking piece 43 having laterally extending ribs44 similar in shape to the ribs 41 of the breech bolt is slidablymounted in vertical guides or grooves 45 of the breech bolt. The ribs 44of the locking piece 43 slide in the grooves 42 and are constrained bythese grooves to the position shown in FIG. 8 throughout the greaterpart of the travel of the bolt. At the forward end of the grooves 42recesses 46 are cut into the side plates 3* and 3 which communicate withthe grooves or which permit the locking piece 43 to rise a limiteddistance out of the grooves 42 so that the laterally extending lugs orribs 44 of the locking piece are engaged in the grooves 46 and the boltis locked in breech-closing position.

The above bolt and locking mechanism can be directly substituted forthat shown in FIGS. 1 to 5, the pin 16 being inserted through lugs 47'at the base of the locking piece to connect the toggle link 15 thereto.The toggle lever 17 and other parts of the mechanism are constructed andarranged as shown in FIGS. 1 to 5.

In the further modified form of my invention shown in FIG. 9, which is atransverse sectional view through the breech portion of the gun similarto FIG. 7 but looking forwardly toward the barrel of the firearm, thebreech bolt 50 is provided with laterally extending guide lugs 51 whichmay also serve in part as locking lugs. One of these lugs is extendedthrough a slot 52 in the plate 3 and provided with a ball 53 on itsextended end. The lugs 51 slide in grooves 54 in the plates of thebarrel extension and these grooves constrain the bolt against turningexcept at the forward end of its travel where recesses 55 are providedcommunicating with the grooves 54 which recesses permit the bolt torotate slightly so as to be locked against its sliding movement in thebarrel extension.

In this form of my invention the toggle link (referred to by the numeral15 in the previously described construction) is in the form of a crankcomprising the members 56, 57 and 58. The member 56 is provided with asocket 59 at its upper end to receive the ball 53 and form a ball andsocket connection with the bolt. The member 57 is in the form of a pinjoining the members 56 and 58 and extends throu h an opening 60 in theplate 3 so that the member 58 lies between the plates of the barrelextension and may be pivotally connected by the pin 18 to the togglelever 17. This pin 18 may be of slack fit in the member 58 to permitslight lateral oscillation of the latter.

While I have shown and described some preferred embodiments of myinvention, it will be understood that it is not to be limited to all ofthe details shown, but is capable of modification and variation withinthe spirit of the invention and within the scope of the claims.

What I claim is: i

1. Operating and locking mechanism for the breech bolt of a firearmhaving a gun casing, a barrel and a barrel extension longitudinallyslidable in the gun casing, and a longitudinally sliding breech boltcarried by said barrel extension and locked to it when in batteryposition, said mechanism including a toggle link connected to the breechbolt to actuate the same, a toggle lever fulcrumed in the barrelextension and pivotally connected to said link, the lever and linkconstituting toggle members, and said fulcrum point of the lever in thebarrel extension being displaced a substantial distance transverselyfrom the barrel axis with respect to the length of the link and being solocated that the toggle members are in substantial alignment when thebreech bolt is in battery position and fold rearwardly wholly upon. thatside of the barrel axis upon which said fulcrum point is located.

2. A breech bolt operating and locking mechanism for a firearm accordingto claim 1 in which said toggle lever is provided beyond its fulcrumpoint with a stub lever at an angle to the toggle lever, and said stublever is oscillatably connected to the gun casing by an actuator linkpivoted to the toggle lever and to the gun casing, and the line joiningthe pivot points of said last-named link being substantiallyperpendicular to the barrel axis when the breech bolt is in batteryposition.

3. A breech bolt operating and locking mechanism for a firearm accordingto claim 2 in which the pivot point of the stub lever to the link isnearer the axis of the barrel when the bolt is in battery position thanthe fulcrum point of the toggle lever.

4. A breech bolt operating and lockingmechanism for a firearm accordingto, claim 1 in whichthe barrel extension is provided with a lockingrecess and the toggle link moves the bolt into saidrecessnat the forwardend of the bolt travel.

5. A breech bolt operating and locking mechanism for a firearm having. agun. casing, a..barre1t and barrel extension longitudinally slidable inthe gun casing, said barrel extension being provided with guide grooves,a breech bolt slidably mounted in said grooves, the grooves being slopedwith respect to the barrel axis so that their rear ends are further fromthe barrel axis than their forward ends, a toggle link pivoted at oneend to the breech bolt, a toggle lever pivoted at one of its ends to theother end of the toggle link, and said lever being fulcrumed in thebarrel extension at a point transversely displaced from the barrel axisa distance greater than the length of the link and in the same radialdirection as the direction of displacement of the guide grooves from thebarrel axis, and said fulcrum point being so located that when thebreech bolt is in forward position the toggle members are in substantialalignment.

6. A breech bolt operating and locking mechanism for a firearm accordingto claim 5 in which the toggle lever is provided, beyond its fulcrumpoint, with a stub lever at an angle to the toggle lever, and said stublever being movably connected to the gun casing by an actuator link,said link being substantially perpendicular to the barrel axis when thebreech bolt is in forward position.

7. A breech bolt operating and locking mechanism for a firearm accordingto claim 5 in which the connection of said actuating link to the stublever is nearer to the axis of the barrel when the bolt is in forwardposition than is the fulcrum point of the toggle lever with the barrelextension.

8. A breech bolt operating and locking mechanism for a firearm accordingto claim 1 in which a locking member is movably mounted in the breechbolt and in which the forward end of the toggle lever is pivoted to saidmember.

9. A breech bolt operating and locking mechanism for a firearm accordingto claim 5 in which a locking member is movably mounted in the breechbolt and in which said member is pivoted to the forward end of thetoggle link.

10. Operating and locking mechanism for the breech bolt of a firearmhaving a gun casing, a barrel and a barrel extension longitudinallyslidable in the gun casing, and a longitudinally sliding breech boltcarried by said barrel extension and locked to it when in batteryposition, said mechanism including a toggle link connected to the breechbolt to actuate the same, a toggle lever fulcrumed in the barrelextension and pivotally connected to said link, the lever and linkconstituting toggle members, said toggle members being in substantialalignment when the bolt is in battery position, and making an acuteangle with the barrel axis in a direction to apply a transversecomponent of movement to the breech bolt to lock it to the barrelassembly.

11. A breech bolt operating and locking mechanism as in claim 1 whereinthe bolt is mounted for rotation relatively to the barrel extension, andthe latter is provided with locking recesses adjacent its forward endinto which the bolt is moved at the end of its forward movement.

12. A breech bolt operation and locking mechanism as set forth in claim1 in which the fulcrum point of the lever in the barrel extension isdisposed forwardly of the point of connection of the toggle link withthe breech bolt when the latter is in recoil position.

13. A breech bolt operating and locking mechanism as in claim 5 in whichthe fulcrum point of the lever in the barrel extension is disposedforwardly of the pivot point of the toggle link with the breech boltwhen the latter is in recoil position.

References Cited in the file of this patent UNITED STATES PATENTS695,784 Bennett et al. Mar. 18, 1902 749,341 Tobisch Jan. 12, 19041,083,872 Berthier Jan. 6, 1914 1,518,498 Furrer Dec. 9, 1924 1,801,071Browning Apr. 14, 1931 FOREIGN PATENTS 211,229 Germany June 28, 190950,429 Austria Oct. 11, 1911

